Circuit breaker



NW 24, 195.3 J. TOTH CIRCUIT BREAKER Filed Oct. 16, 1951 Fig .1.

OFF

INVENTOR Julius Torh.

ATTORNES WITNESSES: 7

Patented Nov. 24, 1953 CIRCUIT BREAKER Julius Toth, Beaver, Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Application October 16, 1951, Serial No. 251,491

13 Claims. 1

This invention relates to circuit breakers and more particularly to circuit breakers which are manually operable to open and close the circuit and which are automatically operated to open the circuit in response to abnormal circuit conditions.

An object of the invention is to provide a 011'- cuit breaker in which a contact member and a releasable member are disposed end to end to i'orm a toggle, the knee of which toggle ismovable over center to effect opening and closmg of the circuit. w

Another object of the invention is to provide a circuit breaker according to the preceding paragraph, in which the toggle formed by the contact carrying'member and the releasable member is manually operated to open and close the circuit.

Another object of the invention is to provide a circuit breaker in which a switch arm and a releasable member are disposed end to'end with an overcenter spring connected therebetween, the members forming a'toggle which is movable over center to open and close the circuit.

Another object of the invention is to provide an improved circuit breaker which requires a minimum number of parts.

Another object of the invention is to provide an improved circuit breaker construction that is simple, reliable in operation and inexpensive to manufacture.

The novel features that are considered characteristic of the invention are set forth in particular in the appended claims. The invention itself, however, both as to structure and operation, together with additional objects and advantages thereof, will be best understood from the following detailed description of one form thereof, when read in conjunction with the accompanying drawing.

In said drawing:

Figure 1 is a vertical sectional View of a circuit breaker embodying the principles of the invention, the circuit breaker being shown in the closed position,

Fig. 2 is a View similar to Fig. 1 but showing the circuit breaker in the tripped open position,

Fig. 3 is a vertical sectional view taken on line III-'II I of Fig. 1 and looking in the direction indicated by the arrows, and

Fig. 4 is a detail plan view of the operating toggle and the overcenter spring.

Referring to the drawing, the circuit breaker comprises generally a base II and a cover [3 of molded insulating material, operating mechanism indicated generally'at I5 and a trip device iii indicated generally at H. A stationary contact i9 is mounted on the inner end of a terminal 2| which extends through an opening in the base I! and is secured thereto by means of a nut 23 threaded into the terminal. I

A cooperating movable contact 25 is carried on a movable switch member 21 which, together with a releasable member 29, forms an operating toggle. An overcenter spring 3| is connected under tension between the switch member 2'! and the releasable member 29 as is more clearly shown in Fig. 4. The members 21 and '29 are bifurcated at their inner ends and the overcenter spring 35 is disposed between the legs of each of the members, as shown in Fig. 4.

Formed outwardly from the right-hand end of the switch member 27 are projections 33 having pivot recesses formed therein for receiving trunnions 35 on the releasable member 29 to form a knee pivot for pivotally connecting the two toggle members 27 and 29 together. The releasable member 29 of the toggle is releasably restrained by the trip device I! and is biased for movement by means of a spring 31 compressed minate in ears 43 with bias upwardly against the knee of the toggle. This biases the knee of the toggle 2l28 upwardly against eccentric portions is of a manual operating handle 41. The

handle is constructed of insulating material and is provided with trunnions 49 disposed in bearing recesses in the side walls of the base H to pivotally support the handle. The handle is held in .place against the bias of the springs 39 and 31 by the side walls of the cover l3 which is secured to the base II by any suitable means such, for instance, as bolts 5|. The handle 41 ha a channel 53 therethrough to accommodate the overcenter spring in the open position of the toggle 21-29.

The circuit breaker is opened manually by clockwise movement of the handle 47 from the on position to the off position shown'in dot and dash lines in Fig. 1. During this movement of the handle 47, the eccentric portions 45 thereof move the knee of the toggle downwardly against the-bias of the spring 39. As soon as the knee of the toggle passes below the center line of the overcenter spring 35, which normally biases the switch-arm 27 to close position, the force-of the ment of the handle, second eccentric portions 55 l of the handle engage the switch member 2'! and move it toward the closed position. At the same time, the eccentric portions 45 move away from the knee of the toggle which, under the influence of the spring 39 moves upwardly with the eccentric portions 45. At a predetermined time during the closing movement, the knee of the toggle passes above the line of action of the overcenter spring 3| whereupon the spring acts to move the switch member 2'! to the closed position with a snap action.

The circuit breaker is tripped open automatically in response to overload currents by means of the strip device ii. The trip device comprises a bimetal element 5! having a mounting foot 55 formed thereon mounted. on the inner end of a terminal 6| extending through the base H and secured thereto by means of a nut 63. A latch 65 is mounted on the bimetal element but is insulated therefrom by a piece of insulating material 61. Also mounted on the bime'tal element 51 is an armature 69 for cooperating with a magnet yoke 'H rigidly supported in the side walls of the housing. The upper end or the bimetal element 51 is connected by means of a ible conductor 13 to the switch member cent to the movable contact 25.

The circuit breaker is tripped open in response to overload currents below a predetermined ve 'ie of, for instance, times normal rated current. Upon the occurrence of such an overload current, the bimetal element 5'! becomes heated, and, wb n heated at predetermined amount, bends toward the right causing the latch 65 to release the re leasable member 29 whereupon the spring 3i im mediately snaps the releasable member to the position in which it is shown in Fig. 2 against a stop l-l. During this movement, the releasable member 29 pivots about the knee of the toggle 2l29 and carries the right hand end of the spring 3| over center above the knee of the toggle, whereupon the force of the biases the switch member 2! in opening direction. and moves it to the open position with a snap action. As the switch member 2! moves to the open position, it rotates the handle 41 to an intermediate indicating position as shown in 2 which illustrates the parts of the breaker in the tripped open position.

Before the contacts may be closed. following an automatic opening operation, it is necessary to reset and relatch the releasable member 29 of the operating toggle. This is accomplished by moving the handle 41 clockwise to the full ofi' position during which movement the handle engages and moves the releasable member 29 clockwise about the knee of the toggle. Near the end of the resetting movement the end of the releasable member wipes by the latch 65 slightly bending the bimetal element 5'! which then springs back to its normal position with the latch 55 in the restraining position. The contacts are then closed in the previouly described manner by counterclockwise movement of the handle to the on position.

When an overload current above the predetermined value of 10 times normal rated current ad, a.-

Lil

on a short circuit current occurs, the electro magnetic means 69ll is energized sufiiciently to cause the magnet yoke H to attract and move the armature 69. This causes bending of the bimetal element 51. This effects release of the re leasable member 29 and instantaneous opening of the breaker. The mechanism is reset and the contacts are closed following an instantaneous tripping operation in the manner previously described.

Means is provided to maintain the proper latch overlap during a resetting operation. As the latch end of the releasable member 29 Wipes by the latch 65 during a resetting operation, the force of the bimetal element might cause the toggle 2l-29 to slide toward the left which, upon relatching, would decrease the latch overlap and thus change the calibration of the trip device. To overcome this tendency, a projection 15 on the releasable member 29 is engaged by the handle 41 to prevent leftward movement of the releasable member 29 during the resetting and relatching movement.

While the invention has been disclosed in accordance with the provisions of the patent statues, it is to be understood that various changes and modifications in the structural details thereof may be made without departing from some of the essential features of the invention.

I claim as my invention:

1. A circuit breaker comprising relatively movable contact means, a switch member movable to efiect opening and closing of said contact means, a releasable member having one end pivotally connected to one end of said switch member, said switch member and said releasable member forming a toggle, an overcenter spring connected to said switch member and to said releasable memher, an operating handle movable to an on" and to an off position for efiecting manual opening and closing of said contact means, spring means biasing the knee of said toggle against said handle, and said handle when moved to said oii position moving the knee of said toggle over center to permit said overcenter spring to move said switch member to open position.

2. A circuit breaker comprising relatively movable contact means, a toggle comprising a switch member for opening and closing said contact means and a releasable member operable when released to efiect opening movement of said switch member, means pivotally connecting said switch member and said releasable member to form a knee pivot for said toggle, an overcenter spring for operating said toggle, a manual operating handle, spring means biasing the knee pivot of said toggle against said operating handle, cam means on said handle operable when said handle is moved to the off position to engage and move the knee pivot of said toggle over center to permit said overcenter spring to move said switch member to open position, and said handle when moved to the on position engaging and moving said switch member to the closed position.

3. A circuit breaker comprising relatively movable contacts, a toggle comprising a switch member and a releasable member operable to open and close said contacts, means forming a knee pivot for said toggle pivotally connecting said switch member and said releasable member, an overcenter spring connected under tension between said switch member and said releasable member and normally biasing said switch member closed, an operating handle movable to an on and an oil position and having a. cam

movable to an on and to an oir position, a spring biasing the laterally movable pivot of said switch member against said handle, said handle when moved to the off position moving the laterally movable pivot for said switch member overcenter relative to said overcenter spring to permit said overcenter spring to move said switch member to open position, and a portion of said handle upon movement thereof to the on position engaging and moving said switch member to the closed position.

11. A circuit breaker comprising relatively movable contacts, a switch member having one end pivoted on a laterally movable pivot and the other end movable about said pivot to open and close said contacts, a releasable member, an overcenter spring connected between said switch member and said releasable member, a pivoted operating handle having an eccentric portion adjacent its pivot, a spring biasing the laterally movable pivot of said switch member against said eccentric portion or said handle, said handle when moved to the off position moving the laterally movable pivot of said switch member overcenter to permit said overcenter spring to move said switch member to open position, and a portion of said handle upon movement thereof to the on" position engaging said switch member at a point near said other end to move said switch member to closed position.

12. A circuit breaker comprising relatively movable contacts, a switch member having one end supported on a laterally movable pivot and the other end movable about said pivot, said switch member being movable to open and close said contacts, a releasable member, a trip device releasably restraining said releasable member, said releasable member being positioned opposite the pivoted end of said switch member in the closed position of said breaker, an overcenter spring connected between said switch member and said releasable member, a pivoted operating handle movable to an on and to an off position having a cam portion disposed adjacent the pivot thereof, a spring biasing said laterally movable pivot of said switch member against said cam portion, movement of said operating handle to said oil position causing said cam portion to move the laterally movable pivot of said switch member overcenter to permit said overcenter spring to move said switch member to open position, said trip device being operable in response to overload currents to release said releasable member, and spring means operable upon release of said releasable member to actuate said releasable member and cause automatic opening movement of said switch member.

13. A circuit breaker comprising relatively movable contacts, a switch member having one end pivotally supported on a laterally movable pivot, said switch member being movable about said laterally movable pivot to open and close said contacts, a releasable member, a trip device releasably restraining said releasable member,

.said releasable member being positioned opposite the pivoted end of said switch member in the closed position of said breaker, an overcenter spring connected between said switch member and said releasable member, a pivoted operating handle movable to an on and to an "011? position having a cam portion disposed adjacent the pivot thereof, a spring biasing said laterally moving pivot of said switch member against said cam portion, movement of said operating handle to said oil position causing said cam portion to move the laterally movable pivot of said switch member overcenter to permit said overcenter spring to move said switch member to open position, said trip device being operable in response to overload currents to release said releasable member, spring means operable upon release of said releasable member to actuate said releasable member and cause automatic opening movement of said switch member, and said handle having spaced portions thereon, one of said portions being engageable with said releasable member to reset said releasable member and the other of said portions being engageable with said switch member to move said switch member to closed position.

JULIUS TOTH.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,182,864 Frank Dec. 12, 1939 2,210,263 Sachs Aug. 6, 1940 2,262,205 Schachtner Nov. 11, 1941 2,504,513 Fleming Apr. 18, 1950 2,534,938 Woodward Dec. 19, 1950 

